Haloperidol is considered to be the drug of choice for the treatment of Tourette Syndrome (TS) although no double-blind studies of its effectiveness compared to placebo or other neuroleptics have been done. With this need in mind, we propose to conduct a randomized, double-blind, parallel study comparing the clinical effectiveness and adverse effects of haloperidol, pimozide and placebo in 90 TS patients. The hypotheses, stated positively, are that haloperidol and pimozide will improve the signs and symptoms of TS significantly more than placebo and that pimozide compared to haloperidol will yield significantly more improvement and fewer akinesic adverse effects. Secondary purposes are to measure and assess the nature of the cognitive impairment associated with the treatment of TS with haloperidol and pimozide, and to retrospectively study the relationship between drug dosage, improvement, adverse effects, and selected demographic and illness-related variables. The study will randomly assign the patients to one of the three treatment conditions. Two clinicians will agree on diagnosis and rating of severity. Multiple measures of improvement and adverse effects will be rated by the treating physician, the patient and two independent judges based on their ratings of videotapes of patients. Tests of cognition will be administered to measure the effect on cognition of haloperidol, pimozide and placebo. Tourette syndrome is a chronic, often disabling illness with onset in childhood. The often bizarre and socially limiting nature of the symptoms can restrict psychosocial, educational and vocational functioning. Severe symptoms can result in low self-esteem, social withdrawal, becoming homebound, and hospitalization. Chronic drug administration is often required to suppress tic symptoms and permit effective functioning. Physicians have a responsibility to prevent disabling adverse effects due to chronic drug administration, especially if these interfere with learning in patients already afflicted with a severe disability. The purpose of this study is to provide data which will allow selection of the least impairing but most effective medication for the treatment of TS and a possible range of optimal dosage to prevent harmful adverse effects.